There are susceptors known in the related art that include a plurality of RF electrodes buried therein and laminated so as to be spaced apart from each other. For example, a susceptor 110 in PTL 1 shown in FIG. 8 includes a ceramic substrate 120 and a circular RF electrode 131 and an annular RF electrode 132 that are buried therein and laminated so as to be spaced apart from each other. The circular RF electrode 131 is connected to a first lead 138 via a first external terminal 136 disposed near the center of the susceptor 110. The annular RF electrode 132 is connected to a second lead 139 via a second external terminal 137 disposed near the center of the susceptor 110. As shown in FIG. 9, the annular RF electrode 132 and the second external terminal 137 are connected together with connection circuits 134 arranged radially and in rotational symmetry. A cylindrical support member 140 is attached to the center of the back surface of the susceptor 110 and accommodates the first lead 138 and the second lead 139. The support member 140 functions to protect the first lead 138 and the second lead 139 from corrosive environments. PTL 1 discusses that the susceptor 110 can create a uniform potential inside the annular RF electrode 132 to reduce the density variation of the resulting plasma, thus allowing uniform plasma treatment over the entire surface of a wafer placed on the susceptor 110. PTL 1 also discusses that the density distribution of the plasma can be well controlled by applying different radio-frequency electrical powers to the circular RF electrode 131 and the annular RF electrode 132.